The US is hoping $25m (£13.5m) will entice someone to grass on Palestinian-Jordanian terrorist Abu Musab al-Zarqawi. Yesterday the US more than doubled the money on offer for Zarqawi again, having already raised the figure from $5m to $10m in March.

The same sum was offered for the capture of Saddam Hussein, but the bodyguard who led US troops to Saddam's bolthole only blew his boss's cover under interrogation. No money for him, then.

Whether the new reward will convince anyone within Zarqawi's Tawhid and Jihad network of terrorists, or among his al-Qaida contacts, to hand him over remains to be seen. Zarqawi is believed to have behind a string of atrocities, including the beheadings of US businessman Nicholas Berg and South Korean hostage Kim Sun-il; the bombing of the UK consulate, a bank and two synagogues in Istanbul; the bombing of the Ali Imam mosque in Najaf and the car bomb attack on the UN headquarters in Baghdad.

The money on offer would be paid by the US state department, which runs a programme - Rewards for Justice - specifically designed to capture terrorists either before or after they carry out an attack. The FBI also regularly offers money for other criminals on its most-wanted list.

Any self-respecting supergrass will want assurances that the money will be in their hands - and being used to purchase Louis Vuitton luggage for the inevitable move into hiding - before they ring the Rewards for Justice hotline. The state department will not discuss individual awards, but claims to have paid out more than $49m in 29 cases in the last seven years.

The largest award paid to date is $30m. The state department refuses to say to whom the sum was paid or for what information, but it is the exact amount offered for Uday and Qusay Hussein, who died in a shootout after someone told the US-led forces where they were hiding.

The US will also pay good money for information leading to the capture of the following people:

Osama bin Laden Reward: $27m The reward includes $25m on offer from the US government and an additional $2m from the Airline Pilots Association and the Air Transport Association.

Mullah OmarReward: $10m The leader of Afghanistan's ousted Taliban government provided a base of operations for Osama bin Laden and his al-Qaida network. In the run up to the US war on Afghanistan, he refused to hand over bin Laden to US authorities.

Izzat Ibrahim al-Duri Reward: £10m A member of Saddam's inner circle, al-Duri is the former vice-chairman of the Iraqi Republican Command council. The US wants him in connection with violent attacks on US forces in Iraq.

Perpetrators the Kenya and Tanzania embassy bombings Reward: $5m each The state department lists 12 men - in addition to Osama bin Laden - wanted for the twin bombings that killed 224 people. Similar rewards are on offer for other terrorist incidents, including the attack on the USS Cole in Yemen.

Preventing an act of terrorism before it happens Reward: Up to $5m in the currency of your choice "We can give you five million reasons to stop terrorism," the Rewards for Justice website says. Providing the US government with information that prevents a terrorist attack can also gain you a new identity and protection for yourself and your family.

Diego Leon Montoya Sanchez Reward: $5m Montoya is wanted by the FBI as a leader of the powerful Colombian Norte de Valle drug cartel.

The FBI pays its debts as well as the state department. The FBI found Theodore Kaczynski, better known as the Unabomber, after a tip-off from his brother, David. No one suggests that David Kaczynski was motivated by the reward - which he may not have known about - but the FBI did pay him $1m. He vowed to use the money to help victims, and would no doubt need to use some of it to pay legal costs.

US authorities, however, are not always so generous. Eric Robert Rudolph is charged with the 1996 Olympic park bombing in Atlanta, which killed one person, and three other bombings in Georgia and Alabama. He was captured by a North Carolina policeman, Jeffrey Postell, on May 31, but as a law enforcement officer, Mr Postell did not see a cent of the £1m reward.